A unified experimental and theoretical approach is employed to explain the pathophysiology caused by arterio-venous fistulae of the dura surrounding the spinal cord. Interstitial fluid pressure is monitored while this pathological shunt between the arterial and venous blood supplies is severed. A bi-phasic continuum model is being developed to explain the observed changes in interstitial fluid pressure following the procedure. The model consists of an equation of motion, a linear constitutive law of the tissue, Darcy's law, the conservation of mass of the tissue network and interstitial fluid and equations describing capillary and lymph transport. Since the model is general, i.e., it predicts the time-course and distribution of interstitial fluid flow, interstitial pressure, elastic stress, tissue displacement and fluid transport, it can describe transport in tumors and tissue edema.